Bluefin Tuna Template, is this it?

[Tesla]

The Bluefin Tuna is one of the fastest long distance swimmers which translates as high efficiency. I haven't perfected the art of overlay, but here's my rough job below, I've included both pic's, so maybe someone can do a better presentation, looks like the Bluefin needs to be rotated slightly to the right.

Even with the rough job it looks pretty good to me, they also lay down all fins at speed into specially designed grooves.

[Frank Lee]

IIRC Bub speed record bike at .09 Cd was modeled after a salmon or a trout.

[Tesla]

Originally Posted by Frank Lee

IIRC Bub speed record bike at .09 Cd was modeled after a salmon or a trout.

I do recall reading something like that, but didn't really register at the time, this just popped out of a little aero trail I started following.

[NeilBlanchard]

Biomimicry is the way to go, I think. I want to mention the boxfish study that Mercedes did - the computer model of the fish had a Cd of 0.06:

[aerohead]

Originally Posted by Frank Lee

IIRC Bub speed record bike at .09 Cd was modeled after a salmon or a trout.

Frank,a fella at Mike Cook's Shootout told me that it was a coho salmon that served as the inspiration for the bikes body.

[aerohead]

For what I have for fish,the authors report the same thing,that the bluefin has the lowest drag form of all the pelagic fish.
The bummer is trying to locate plan views of the fish,as most of the water goes around their sides rather than below or over.These views would really show where the action is,and frustrates a complete analysis.

[Tesla]

Originally Posted by aerohead

For what I have for fish,the authors report the same thing,that the bluefin has the lowest drag form of all the pelagic fish.
The bummer is trying to locate plan views of the fish,as most of the water goes around their sides rather than below or over.These views would really show where the action is,and frustrates a complete analysis.

Just had a look around, here's best I could find on a quick look:




Description from site:

DORSAL WALL OF BODY CAVITY

The roof of the body cavity was, in cross section, convex in all three varieties. The convexity began abruptly with the origin of the haemal canal and was greatest in this region, diminishing progressively toward the posterior portion of the cavity. The upper sketches, a, of Figure 4, depict diagrammatically the shape of the dorsal wall of the body cavity viewed in a longitudinal section cut through the vertical median plane of the fish.

Anterior to the ninth or tenth vertebra the roof of the body cavity was, in cross section, relatively flat. With the origin of the haemal canal on the tenth vertebra the roof of the body cavity sloped abruptly downward, and from this point posteriorly the depth of the haemal spines determined the level of the dorsal wall of the cavity. This ventral bulge was not confined to the median line. It extended transversely toward the belly wall, but was separated from the latter by a depression on either side (Figure 4, b and c). This depression was formed mesially by the side of the ventral bulge and laterally by the belly wall. It was in the shape of the bulge, and in the size and shape of the depression that the varieties differed.

Site Link:
A Comparison of the Bluefin Tunas, Genus Thunnus From New England, Australia and California1

[Tesla]

Just a bit more:





And here's a quote from the site, studying different swimming actions in fish, think you'll like the bit about the Fineness Ratio:

o Thunniform: Lateral movement of the torso is limited to the caudal peduncle (tail) and fin. The caudal fin is semilunate - i.e. tall and half-moon shaped.
In thunniform swimmers, water displacement is achieved by lift, generated by the caudal fin, rather than drag. The caudal fin has a high aspect ratio (span of fin/chord). Because lift is more efficient at higher speeds and Reynolds numbers, the thunniform morph is optimized for high absolute speed. The body must be highly streamlined. Indeed, even the caudal peduncle, the source of drag displacement in slower swimmers, is streamlined to reduce drag in its side-to-side motion. The strong selection for streamlining results in a typical maximum fineness ratio (diameter/length) of .25 at about 1/3 of the body's length. Example tuna.

Biology of Extinct Animals

[aerohead]

Thanks alot!
These are the first I've seen after years of waiting.
The Edison-2 folks will enjoy the reflexed camber in the aft-body.
My chart showed a Length/Width ratio a little smaller but close to 4.
This is the ratio of lowest drag for sections and struts.Fun coincidence!

[aerohead]

One of my books about sharks presented the following data:
These marine creatures are presented according to their body length,divided by there maximum body width as measured from above (plan-view)
*Bluefin tuna--------------------------------------------------- 3.571:1
*Swordfish----------------------------------------------------- 4.166:1
*White shark (JAWS) ------------------------------------------- 3.846:1
*Cod ----------------------------------------------------------- 6.25:1
*Mackerel ------------------------------------------------------ 7.142:1
*Eel ------------------------------------------------------------ 20.0:1
*Blue whale -----------------------------------------------------4.76:1
*Bottle-nosed dolphin --------------------------------------------4.00:1
*Emperor penguin ------------------------------------------------3.846:1
*Harp seal ------------------------------------------------------ 4.166:1
--------------------------------------------------------------------------
According to Sighard Hoerner,a symmetrical wing section or strut would have a drag minimum at L/W= 4.00.
You can see from the list that six of the listed swimmers are near this drag minimum.